Apparatus for controlling the inflow of production fluids from a subterranean well

ABSTRACT

A fluid flow control apparatus ( 100 ) for controlling the inflow of production fluids from a subterranean well includes a fluid discriminator section ( 104 ) and a flow restrictor section ( 106 ) that is configured in series with the fluid discriminator section ( 104 ) such that fluid must pass through the fluid discriminator section ( 104 ) prior to passing through the flow restrictor section ( 106 ). The fluid discriminator section ( 104 ) is operable to autonomously restrict at least a portion of an undesired fluid type, such as water or gas, from the production fluids. The flow restrictor section ( 106 ) is operable to restrict the flow rate of the production fluids, thereby minimizing the pressure drop across the fluid discriminator section ( 104 ).

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation-in-part application of co-pending application Ser. No. 11/466,022 filed Aug. 21, 2006 entitled Autonomous Inflow Restrictors for Use in a Subterranean Well, the entire contents of which is hereby incorporated by reference.

TECHNICAL FIELD OF THE INVENTION

This invention relates, in general, to controlling the production of fluids from a well that traverses a hydrocarbon bearing subterranean formation and, in particular, to an apparatus for controlling the flow rate and constituent composition of production fluids from the subterranean well.

BACKGROUND OF THE INVENTION

Without limiting the scope of the present invention, its background will be described with reference to producing fluid from a subterranean formation, as an example.

During the completion of a well that traverses a hydrocarbon bearing subterranean formation, production tubing and various equipment are installed in the well to enable safe and efficient production of the formation fluids. For example, to prevent the production of particulate material from an unconsolidated or loosely consolidated subterranean formation, certain completions include one or more sand control screens positioned proximate the desired production intervals. In other completions, to control the flow rate of production fluids into the production tubing, it is common practice to install one or more flow control devices within the tubing string.

Recently, attempts have been made to utilize fluid flow control devices within completions requiring sand control. For example, in one such device, after production fluids flows through the filter media of the sand control screen, the fluids are directed into a flow control labyrinth. A slidable sleeve on the labyrinth controls the fluid velocity therethrough. The slidable sleeve is moved by a remotely and electrically-operated device placed in the sand control screen. The fluid leaving the labyrinth passes to the tubing string for carrying to the surface. While certain benefits have been achieved through the use of such devices, many of these devices are complicated to operate and have suffered from poor reliability.

Accordingly, need has arisen for a fluid flow control device for controlling the inflow of formation fluids in a completion requiring sand control. A need has also arisen for such a fluid flow control device that is not difficult or expensive to manufacture. Further, a need has arisen for such a fluid flow control device that is reliable in a variety of flow conditions.

SUMMARY OF THE INVENTION

The present invention disclosed herein comprises a flow control apparatus for controlling the inflow of formation fluids in completions requiring sand control. The flow control apparatus of the present invention is not difficult or expensive to manufacture. In addition, the flow control apparatus of the present invention is reliable in a variety of flow conditions.

In one aspect, the present invention is directed to a flow control apparatus for controlling the inflow of production fluids from a subterranean well that includes a fluid discriminator section and a flow restrictor section configured in series with the fluid discriminator section such that fluid must pass through the fluid discriminator section prior to passing through the flow restrictor section. The fluid discriminator section is operable to autonomously restrict at least a portion of an undesired fluid type from the production fluids. The flow restrictor section is operable to restrict the flow rate of the production fluids.

In one embodiment of the flow control apparatus, the fluid discriminator section includes a substantially circumferential chamber having a plurality of circumferentially distributed outlets and a plurality of blocking members disposed within the substantially circumferential chamber. In this embodiment, at least a portion of the blocking members may have a density greater than that of oil. Alternatively or additionally, a portion of the blocking members may have a density less than that of oil. In another embodiment, a first portion of the blocking members may have a weight that is greater than that of a second portion of the blocking members. In certain embodiments, spacer members may be disposed between at least some of the blocking members. The blocking members may be formed in a variety of shapes including spherically shaped blocking members, cylindrically shaped blocking members and partially circumferentially shaped blocking members.

In another embodiment of the flow control apparatus, the flow restrictor section includes a passageway. In one embodiment, the passageway has an effective flow area less than twenty five percent of an unrestricted effective flow area of the fluid discriminator section. In another embodiment, the passageway has an effective flow area less than ten percent of an unrestricted effective flow area of the fluid discriminator section. In certain embodiments, the passageway may be a helical passageway or may include a plurality of helical passageways.

In another aspect, the present invention is directed to a flow control apparatus for controlling the inflow of production fluids from a subterranean well that includes a sand control screen element, a fluid discriminator section configured in series with the sand control screen element such that fluid must pass through the sand control screen element prior to passing through the fluid discriminator section. A flow restrictor section is configured in series with the fluid discriminator section such that fluid must pass through the fluid discriminator section prior to passing through the flow restrictor section. The fluid discriminator section is operable to autonomously restrict at least a portion of an undesired fluid type from the production fluids. The flow restrictor section is operable to restrict the flow rate of the production fluids.

In one embodiment, the fluid discriminator section includes a substantially circumferential chamber having a plurality of circumferentially distributed outlets and a plurality of blocking members disposed within the substantially circumferential chamber that cooperate with the outlets to autonomously restrict the at least a portion of the undesired fluid type from the production fluids.

In a further aspect, the present invention is directed to a flow control apparatus for controlling the inflow of production fluids from a subterranean well that includes a fluid discriminator section and a flow restrictor section configured in series with the fluid discriminator section such that fluid must pass through the fluid discriminator section prior to passing through the flow restrictor section. The fluid discriminator section includes a substantially circumferential chamber having a plurality of circumferentially distributed outlets and a plurality of blocking members disposed within the substantially circumferential chamber that cooperate with the outlets to autonomously restrict at least a portion of an undesired fluid type from the production fluids. The flow restrictor section includes a helical passageway having an effective flow area less than twenty five percent of an unrestricted effective flow area of the fluid discriminator section such that the flow restrictor section is operable to restrict the flow rate of the production fluids.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which:

FIG. 1 is a schematic illustration of a well system operating a plurality of fluid flow control devices according to the present invention;

FIG. 2A is side view partially in quarter section and partially in half section of a fluid flow control device according to the present invention;

FIG. 2B is a cross sectional view of the fluid flow control device of FIG. 2A taken along line 2B-2B;

FIG. 2C is a cross sectional view of the fluid flow control device of FIG. 2A taken along line 2B-2B during two phase flow of oil and water;

FIG. 2D is a cross sectional view of the fluid flow control device of FIG. 2A taken along line 2B-2B during three phase flow of oil, gas and water;

FIG. 3A is side view partially in quarter section and partially in half section of a fluid flow control device according to the present invention;

FIG. 3B is a cross sectional view of the fluid flow control device of FIG. 3A taken along line 3B-3B;

FIG. 4A is side view partially in quarter section and partially in half section of a fluid flow control device according to the present invention;

FIG. 4B is a cross sectional view of the fluid flow control device of FIG. 4A taken along line 4B-4B;

FIG. 5A is side view partially in quarter section and partially in half section of a fluid flow control device according to the present invention;

FIG. 5B is a cross sectional view of the fluid flow control device of FIG. 5A taken along line 5B-5B;

FIG. 6A is side view partially in quarter section and partially in half section of a fluid flow control device according to the present invention; and

FIG. 6B is a cross sectional view of the fluid flow control device of FIG. 6A taken along line 6B-6B.

DETAILED DESCRIPTION OF THE INVENTION

While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention.

Referring initially to FIG. 1, therein is depicted a well system including a plurality of fluid flow control devices embodying principles of the present invention that is schematically illustrated and generally designated 10. In the illustrated embodiment, a wellbore 12 extends through the various earth strata. Wellbore 12 has a substantially vertical section 14, the upper portion of which has installed therein a casing string 16. Wellbore 12 also has a substantially horizontal section 18 that extends through a hydrocarbon bearing subterranean formation 20. As illustrated, substantially horizontal section 18 of wellbore 12 is open hole.

Positioned within wellbore 12 and extending from the surface is a tubing string 22. Tubing string 22 provides a conduit for formation fluids to travel from formation 20 to the surface. Positioned within tubing string 22 in the various production intervals adjacent to formation 20 are a plurality of fluid flow control devices 24. On either side of each fluid flow control device 24 is a packer 26 that provides a fluid seal between tubing string 22 and the wall of wellbore 12. Each pair of adjacent packers 26 defines a production interval. Through use of the fluid flow control devices of the present invention and by providing numerous production intervals, precise control over the volume and composition of the produced fluids is enabled. For example, in an oil production operation if an undesired fluid component, such as water or gas, is entering one of the production intervals, the fluid flow control device in that interval will autonomously restrict the production of that undesired fluid component and in some cases the entire fluid stream from the production interval.

Accordingly, when a production interval corresponding to a particular one of the fluid flow control devices produces a greater proportion of an undesired fluid, the fluid flow control devices in that interval will increasingly restrict flow from that interval. Thus, the other production intervals which are producing a greater proportion of desired fluid, in this case oil, will contribute more to the production stream entering tubing string 22. In particular, there will be a greater pressure drop from formation 20 to tubing string 22, resulting in a greater production of the desired fluid, due to the increased restriction to flow from the production interval producing a greater proportion of the undesired fluid.

In the illustrated embodiment, each of the fluid flow control devices 24 provides not only fluid flow control capability but also sand control capability. The sand control screen elements or filter media associated with fluid flow control devices 24 are designed to allow fluids to flow therethrough but prevent particulate matter of sufficient size from flowing therethrough. The exact design of the screen element associated with fluid flow control devices 24 is not critical to the present invention as long as it is suitably designed for the characteristics of the formation fluids and any treatment operations to be performed. For example, the sand control screen may utilize a nonperforated base pipe having a wire wrapped around a plurality of ribs positioned circumferentially around the base pipe that provide stand off between the base pipe and the wire wrap. Alternatively, a fluid-porous, particulate restricting, sintered metal material such as a plurality of layers of a wire mesh that are sintered together to form a fluid porous wire mesh screen could be used as the filter medium. As illustrated, a protective outer shroud having a plurality of perforations therethrough may be positioned around the exterior of the filter medium.

Even though FIG. 1 depicts the fluid flow control devices of the present invention in an open hole environment, it should be understood by those skilled in the art that the fluid flow control devices of the present invention are equally well suited for use in cased wells. Also, even though FIG. 1 depicts one fluid flow control device in each production interval, it should be understood by those skilled in the art that any number of fluid flow control devices of the present invention may be deployed within a production interval without departing from the principles of the present invention.

In addition, even though FIG. 1 depicts the fluid flow control devices of the present invention in a horizontal section of the wellbore, it should be understood by those skilled in the art that the fluid flow control devices of the present invention are equally well suited for use in deviated or vertical wellbores. Accordingly, it should be understood by those skilled in the art that the use of directional terms such as above, below, upper, lower, upward, downward and the like are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being toward the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure. Further, even though FIG. 1 depicts the fluid flow control devices of the present invention as including sand control screen elements, it should be understood by those skilled in the art that the fluid flow control devices of the present invention are equally well suited for use apart from the sand control screen elements.

Referring next to FIGS. 2A-2B, therein is depicted a fluid flow control device according to the present invention that is representatively illustrated and generally designated 100. Fluid flow control device 100 may be suitably coupled to other similar fluid flow control devices, production packers, production tubulars or other downhole tools to form a tubing string as described above. Fluid flow control device 100 includes a sand control screen section 102, a fluid discriminator section 104, a flow restrictor section 106 and a fluid inlet section 108. Sand control screen section 102 includes a suitable sand control screen element or filter medium, such as a wire wrap screen, a woven wire mesh screen or the like, designed to allow fluids to flow therethrough but prevent particulate matter of sufficient size from flowing therethrough. In the illustrated embodiment, a protective outer shroud 110 having a plurality of perforations 112 is positioned around the exterior of the filter medium.

Fluid discriminator section 104 is configured in series with sand control screen section 102 such that fluid must pass through sand control screen section 102 prior to entering fluid discriminator section 104. Fluid discriminator section 104 includes an outer housing 114 that defines an annular chamber 116 with a nonperforated section of base pipe 118. Fluid discriminator section 104 also includes retainer rings 120, 121. Retainer ring 120 has a plurality of outlets 122 circumferentially spaced therein. Outlets 122 are designed to provide a fluid passageway from chamber 116 to flow restrictor section 106. Each of the outlets 122 has a predetermined effective flow area. Together, the effective flow areas of all the outlets 122 define the unrestricted effective flow area of fluid discriminator section 104. As used herein the term effective flow area refers to the combined influence of the length of a flow restriction and the cross-sectional flow area of the flow restriction under Darcy's law wherein a proportional relationship exists between the instantaneous discharge rate through a porous medium, the viscosity of the fluid and the pressure drop over a given distance.

One or more flow blocking members 124, depicted as spherical members or balls are disposed within chamber 116 between retainer rings 120, 121 and cooperate with outlets 122 to restrict the flow of any undesired portion of the production fluid that enter fluid discriminator section 104. For example, when the desired fluid component of oil is produced along with an undesirable fluid component of water, the density of members 124 is such that certain of the outlets 122 are blocked by certain of the members 124 to shut off or choke the flow of water therethrough. As explained in greater detail below, the density of each of the members 124 is preferably greater than that of the oil, enabling each to either maintain a position within chamber 116 distant from outlets 122 when either no water or only a very small proportion of water is present in chamber 116, or a position shutting off or choking flow through outlets 122 when a larger proportion of water is present in chamber 116. Thus, when the production fluid is mainly oil, members 124 will be positioned relatively distant from outlets 122, for example, at the bottom of chamber 116. When a sufficient proportion of water is present in the production fluid, however, members 124 will restrict flow of the water by shutting off or choking flow through certain ones of the outlets 122.

Flow restrictor section 106 is configured in series with fluid discriminator section 104 such that fluid must pass through fluid discriminator section 104 prior to entering flow restrictor section 106. Flow restrictor section 106 includes an outer housing 126 that is suitably coupled to outer housing 114 of fluid discriminator section 104. Outer housing 126 defines an annular chamber 128 with a nonperforated section of base pipe 118. Disposed within chamber 128 is an annular flow rate controller 130. Flow rate controller 130 includes one or more passageways 132 through which the production fluid must travel. In the illustrated embodiment, the passageways 132 are in the form of helical passageways that provide a relative long pathway for the fluids to travel as the fluid must travel circumferentially within flow restrictor section 106. The one or more passageways 132, each have an effective flow area, the sum of which is preferably less than twenty five percent of the unrestricted effective flow area of fluid discriminator section 104 and more preferably less than ten percent of the unrestricted effective flow area of fluid discriminator section 104. As such, flow restrictor section 106 is operable to restrict the flow rate of the production fluids through fluid flow control device 100.

The use of the highly restrictive flow rate controller 130 in flow restrictor section 106 creates a large pressure drop in the production fluid stream through fluid flow control device 100. At the same time, since the effective flow area through fluid discriminator section 104 is much larger, the production fluid stream experiences a relatively small pressure drop passing through fluid discriminator section 104. This is true even as a first group of members 124 begin to seat on certain of the outlets 122 to preferentially reduce the flow of the undesired fluid therethrough. As the number of outlets 122 being blocked by members 124 approaches the total number of outlets 122, the pressure drop through fluid discriminator section 104 approaches and becomes more significant than the pressure drop through flow restrictor section 106.

Once the production fluids pass through flow rate controller 130 of flow restrictor section 106, they enter annular chamber 134 and eventually enter the interior of base pipe 118 via openings 136 which are depicted in the form of slots. Once inside base pipe 118, the production fluids flow to the surface within the tubing string.

Even though flow rate controller 130 has been described as including one or more helical passageways, it should be understood by those skilled in the art that the flow rate controller of the present invention could alternatively utilize other types of passageways without departing from the principles of the present invention. For example, the passageways could comprise one or more straight passageways such as those provided by flow tubes, one or more passageways having reversals in direction or other labyrinth type structures and the like. In addition, flow rate controller 130 of the present invention could employ passageways in the form of nozzles, ports or other types of flow restrictors.

Referring now to FIGS. 2B-2D, the operation of fluid flow control device 100 in various flow regimes and with various configurations of flow blocking members 124 will now be described. FIG. 2B depicts a flow regime in which all or nearly all of the production fluid is oil. Members 124 are preferably not buoyant as long as the well is producing a sufficient proportion of oil. As can be seen, members 124 are substantially positioned in a bottom portion of chamber 116 and generally at distance from most of the outlets 122. This result is achieved by forming members 124 to have a density that is greater than that of oil and preferably about that of the water expected to be produced or at least of a density between the density of water and the density of oil. For example, the density of members 124 may preferably be about 1030 kg/m³.

As best seen in FIG. 2C, as water is produced into fluid flow control device 100 members 124 provide the capability of increasingly restricting flow of fluid therethrough. When the density of the produced fluid increases by a sufficient amount, members 124 become neutrally buoyant and are carried by the water phase and engage outlets 122, due to the pressure drop across the outlets, thereby restricting flow of the production fluid therethrough. Neutral buoyancy of members 124 only occurs when a sufficient proportion of water is produced. As illustrated, member 124 have engaged the lowest five outlets 122. In some instances, as the water rate may increase slowly, it is possible to continue to produce the oil fraction through the upper outlets 122 while preferentially blocking the water fraction as is shown in FIG. 2C. Specifically, an oil and water interface level exists within fluid flow control device 100 near the locations identified as 138, 140.

In other instances, sufficient water will be produced such that all of the outlets 122 would be blocked. Thus, when the production fluid contains an undesirable fluid such as water, restriction to flow through fluid flow control device 100 increases. A greater proportion of undesirable fluids in the produced fluid results in a greater restriction to flow through fluid flow control device 100. This results in production from those production intervals producing undesirable fluids being reduced due to the increased restriction to flow through its corresponding fluid flow control device 100, while production from other production intervals producing more desirable fluids is increased due to the overall pressure drop as a given fluid flow control device 100 nears complete closedown.

In some instances, a complete closedown of production is not wanted no matter how great the proportion of the undesired fluid. In such instances, the number of members 124 can be less than the number of outlets 122. This effectively provides for certain of the outlets 122 to serve as bypass outlets, thereby allowing for some production, even though members 124 may have shut off or choked flow through the remaining outlets 122. In this example, the number of outlets 122 serving as bypass outlets may be such that the flow rate constriction through fluid discriminator section 104 is less than or greater than the flow rate constriction through flow restrictor section 106.

As best seen in FIG. 2D, the production fluid is depicted as being stratified in chamber 116 into a layer of water at the bottom, a layer of oil in the middle and a layer of gas at the top. As illustrated, some of the members 124 are blocking or at least increasingly restricting flow of gas through the upper three outlets 122 and some of the members 124 are blocking or at least increasingly restricting flow of the water through the lower five outlets 122. In this embodiment, not all the members 124 have the same density. Preferably, certain of the members 124 have a density of about 600 kg/m³ to about 800 kg/m³, which is generally between the density of oil and the density of gas. By selecting an average density preferable from about 600 kg/m³ to about 800 kg/m³, and by keeping in mind that the density of oil is typically somewhat less than 900 kg/m³, these members 124 will be in a buoyant or free-floating state as long as the gas included in the fluid does not lower the overall density of the production fluid below the selected member density. On the other hand, if the influx of gas should result in an overall density of the fluid approximately equal to the member density, then these members 124 will have neutral buoyancy and will nonetheless be dragged to the upper outlets 122 due to the pressure drop thereacross.

As illustrated, since the density of certain members 124 is between the density of oil and the density of gas, some of these members 124 will be positioned at the interface between the oil and gas near the locations identified as 142, 144. If the interface descends in chamber 116 due to an increase in the proportion of gas in the production fluids, an increasing number of upper outlets 122 will be blocked by members 124. Likewise, if the interface ascends in chamber 116 due to an increasing proportion of oil and/or water in the production fluids, a decreasing number of the upper outlets 122 will be blocked by members 124.

As described above, certain of the members 124 have a density that is greater than that of oil and preferably about that of the water expected to be produced or at least of a density between the density of water and the density of oil. For example, the density of theses members 124 may preferably be about 1030 kg/m³. As illustrated, these members 124 have engaged the lowest five outlets 122. In addition, other of these members 124 are neutral buoyancy at an oil and water interface level within chamber 116 near the locations identified as 146, 148. If the interface between the water and oil ascends in chamber 116 due to an increased production of water, an increasing number of lower outlets 122 will be blocked by members 124. If the interface descends in chamber 116 due to an increase in oil and/or gas production, a decreasing number of the lower outlets 122 will be blocked by members 124.

As discussed above, in some instances a complete closedown of production is not wanted no matter how great the proportion of the undesired fluid or fluids. In the embodiment of FIG. 2D, instead of certain of the outlets 122 serving as bypass outlets, it is preferred to have an incomplete seal created between members 124 and some or all of the outlets 122. In this manner, the engagement of members 124 with outlets 122 creates an increased restriction to flow, without completely preventing flow. Thus, some of the gas is permitted to flow through the upper outlets 122 which are engaged by members 124 and some of the water is permitted to flow through the lower outlets 122 which are also engaged by members 124, but these flows are very restricted.

Thus, the fluid flow control device of the present invention provides multiple benefits. As a first group of outlets 122 becomes blocked by members 124 due to the initial production of undesired fluids into a particular production interval, the pressure drop in the fluids passing through that fluid flow control device is predominately affected by its flow restrictor section. As such, the pressure drop associated with that fluid flow control device will not significantly change and will therefore have little effect on production from other production intervals. When most of the outlets 122 become blocked by members 124 due to significant production of undesired fluids into a particular production interval, the fluid discriminator section becomes the primary factor in the overall pressure drop associated with that fluid flow control device, thereby providing a larger pressure drop across that fluid flow control device, which increases the pressure drop across other production intervals in the well, allowing greater production from oil producing zones.

Even though members 124 have been described as having discrete densities based upon their desired service, it should be understood by those skilled in the art that all of the members intended to block gas production do not necessarily have the same density and all of the members intended to block water production do not necessarily have the same density. Instead, the members in each category could have a range of different densities so that the members are neutrally buoyant in different densities of production fluids. In this manner, a greater number of the members intended to block water production would be available to block or restrict flow of the production fluid having a greater proportion of water, and a greater number of the members intended to block gas production would be available to block or restrict flow of the production fluid having a greater proportion of gas.

Referring next to FIGS. 3A-3B, therein is depicted a fluid flow control device according to the present invention that is representatively illustrated and generally designated 200. Fluid flow control device 200 may be suitably coupled to other similar fluid flow control devices, production packers, production tubulars or other downhole tools to form a tubing string as described above. Fluid flow control device 200 includes a sand control screen section 202, a fluid discriminator section 204, a flow restrictor section 206 and a fluid inlet section 208. Sand control screen section 202 includes a suitable sand control screen element or filter medium and is illustrated as including a protective outer shroud 210 having a plurality of perforations 212 positioned around the exterior of the filter medium.

Fluid discriminator section 204 is configured in series with sand control screen section 202 such that fluid must pass through sand control screen section 202 prior to entering fluid discriminator section 204. Fluid discriminator section 204 includes an outer housing 214 that defines an annular chamber 216 with a nonperforated section of base pipe 218. Fluid discriminator section 204 also includes retainer rings 220, 221. Retainer ring 220 has a plurality of outlets 222 circumferentially spaced therein designed to provide a fluid passageway from chamber 216 to flow restrictor section 206.

One or more flow blocking members 224, depicted as spherical members or balls are disposed within chamber 216 between retainer rings 220, 221 and cooperate with outlets 222 to restrict the flow of any undesired portion of the production fluids that enter fluid discriminator section 204. As explained above, in the case of a production fluid containing both oil and water, the density of members 224 is such that certain of the outlets 222 are blocked by certain of the members 224 to shut off or choke the flow of water therethrough. Thus, when the production fluid is mainly oil, members 224 will be positioned relatively distant from outlets 222, for example, at the bottom of chamber 216. When a sufficient proportion of water is present in the production fluid, however, members 224 will restrict flow of the water by shutting off or choking flow through certain ones of the outlets 222.

Flow restrictor section 206 is configured in series with fluid discriminator section 204 such that fluid must pass through fluid discriminator section 204 prior to entering flow restrictor section 206. Flow restrictor section 206 includes an outer housing 226 that is suitably coupled to outer housing 214 of fluid discriminator section 204. Outer housing 226 defines an annular chamber 228 with a nonperforated section of base pipe 218. Disposed within chamber 228 is an annular flow rate controller 230. Flow rate controller 230 includes one or more helical passageways 232 that provide a relative long pathway for the fluids to travel within flow restrictor section 206 and that provide a more restrictive pathway than the unrestricted pathway through fluid discriminator section 204 in a manner similar to that described above with reference to flow restrictor section 106 and fluid discriminator section 104. As such, flow restrictor section 206 is operable to restrict the flow rate of the production fluids through fluid flow control device 200.

Once the production fluids pass through flow rate controller 230 of flow restrictor section 206, they enter annular chamber 234 and eventually enter the interior of base pipe 218 via openings 236 which are depicted in the form of slots. Once inside base pipe 218, the production fluids flow to the surface within the tubing string.

As with fluid flow control device 100 of FIG. 2, fluid flow control device 200 is operable in various flow regimes and with various configurations of flow blocking members 224. For example, members 224 may have a single density and be designed to block a single type of undesirable fluid such as water or gas in an oil production operation, or may have two densities and be designed to block multiple types of undesirable fluids such as water and gas in an oil production operation. Also, all of the members intended to block a certain undesired fluid do not necessarily have the same density. Instead, the members in each category could have a range of different densities so that the members are neutrally buoyant in different densities of production fluids. The embodiment illustrated in FIG. 3 is particularly suitable for use with members 224 having multiple densities. Unlike the embodiment of FIG. 2 in which members 124 are confined within a narrow chamber 116, members 224 can more freely organize themselves within the wider chamber 216 such that the use of more members 224 having a greater variety of densities enables greater control over the production fluids passing therethrough.

Referring next to FIGS. 4A-4B, therein is depicted a fluid flow control device according to the present invention that is representatively illustrated and generally designated 300. Fluid flow control device 300 may be suitably coupled to other similar fluid flow control devices, production packers, production tubulars or other downhole tools to form a tubing string as described above. Fluid flow control device 300 includes a sand control screen section 302, a fluid discriminator section 304, a flow restrictor section 306 and a fluid inlet section 308. Sand control screen section 302 includes a suitable sand control screen element or filter medium and is illustrated as including a protective outer shroud 310 having a plurality of perforations 312 positioned around the exterior of the filter medium.

Fluid discriminator section 304 is configured in series with sand control screen section 302 such that fluid must pass through sand control screen section 302 prior to entering fluid discriminator section 304. Fluid discriminator section 304 includes an outer housing 314 that defines an annular chamber 316 with a nonperforated section of base pipe 318. Fluid discriminator section 304 also includes retainer rings 320, 321. Retainer ring 320 has a plurality of outlets 322 circumferentially spaced therein designed to provide a fluid passageway from chamber 316 to flow restrictor section 306. Disposed within chamber 316 between retainer rings 320, 321 and designed to cooperate with outlets 322 to restrict the flow of any undesired portion of the production fluids that enter fluid discriminator section 304 is a plurality of flow blocking members 324, depicted as spherical members or balls.

Flow restrictor section 306 is configured in series with fluid discriminator section 304 such that fluid must pass through fluid discriminator section 304 prior to entering flow restrictor section 306. Flow restrictor section 306 includes an outer housing 326 that is suitably coupled to outer housing 314 of fluid discriminator section 304. Outer housing 326 defines an annular chamber 328 with a nonperforated section of base pipe 318. Disposed within chamber 328 is an annular flow rate controller 330. Flow rate controller 330 includes one or more helical passageways 332 that provide a relative long pathway for the fluids to travel within flow restrictor section 306 and that provide a more restrictive pathway than the unrestricted pathway through fluid discriminator section 304 in a manner similar to that described above with reference to flow restrictor section 106 and fluid discriminator section 104. As such, flow restrictor section 306 is operable to restrict the flow rate of the production fluids through fluid flow control device 300.

Once the production fluids pass through flow rate controller 330 of flow restrictor section 306, they enter annular chamber 334 and eventually enter the interior of base pipe 318 via openings 336 which are depicted in the form of slots. Once inside base pipe 318, the production fluids flow to the surface within the tubing string.

Unlike the previous embodiments, fluid flow control device 300 of FIG. 4, is specifically designed for operation in three phase flow. As illustrated, one group of members 324 is separated from another group of members 324 by a pair of spacers 338. Spacers 338 each have a flow path therethrough that provides for fluid communication from chamber 316 to outlets 322. The system of members 324 and spacers 338 are relatively tightly received between retainer rings 320, 321 simulating the action of ball bearings in a race. In the illustrated embodiment, the system of members 324 and spacers 338 is self orienting based upon the flow regime within fluid flow control device 300, gravity or both. For example, each of the members 324 above spacers 338 may have a density less than that of oil while the members 324 below spacers 338 may have a density greater than that of oil. Alternatively or additionally, certain of the members 324 below spacers 338 may have a substantially greater weight than any of the other members 324 such that in a horizontal implementation, the self orientation results in the configuration depicted in FIG. 4B.

In either embodiment, members 324 are designed to cooperate with outlets 322 to block or at least restrict the production of the undesired fluid streams of water and gas in an oil production operation. Specifically, the members 324 above spacers 338 are intended to block or at least restrict the production of gas while the members 324 below spacers 338 are intended to block or at least restrict the production of water.

Referring next to FIGS. 5A-5B, therein is depicted a fluid flow control device according to the present invention that is representatively illustrated and generally designated 400. Fluid flow control device 400 may be suitably coupled to other similar fluid flow control devices, production packers, production tubulars or other downhole tools to form a tubing string as described above. Fluid flow control device 400 includes a sand control screen section 402, a fluid discriminator section 404, a flow restrictor section 406 and a fluid inlet section 408. Sand control screen section 402 includes a suitable sand control screen element or filter medium and is illustrated as including a protective outer shroud 410 having a plurality of perforations 412 positioned around the exterior of the filter medium.

Fluid discriminator section 404 is configured in series with sand control screen section 402 such that fluid must pass through sand control screen section 402 prior to entering fluid discriminator section 404. Fluid discriminator section 404 includes an outer housing 414 that defines an annular chamber 416 with a nonperforated section of base pipe 418. Fluid discriminator section 404 also includes retainer rings 420, 421. Retainer ring 420 has a plurality of outlets 422 circumferentially spaced therein designed to provide a fluid passageway from chamber 416 to flow restrictor section 406. Disposed within chamber 416 between retainer rings 420, 421 and designed to cooperate with outlets 422 to restrict the flow of any undesired portion of the production fluids that enter fluid discriminator section 404 is a plurality of flow blocking members 424, depicted as cylindrical members.

Flow restrictor section 406 is configured in series with fluid discriminator section 404 such that fluid must pass through fluid discriminator section 404 prior to entering flow restrictor section 406. Flow restrictor section 406 includes an outer housing 426 that is suitably coupled to outer housing 414 of fluid discriminator section 404. Outer housing 426 defines an annular chamber 428 with a nonperforated section of base pipe 418. Disposed within chamber 428 is an annular flow rate controller 430. Flow rate controller 430 includes one or more helical passageways 432 that provide a relative long pathway for the fluids to travel within flow restrictor section 406 and that provide a more restrictive pathway than the unrestricted pathway through fluid discriminator section 404 in a manner similar to that described above with reference to flow restrictor section 106 and fluid discriminator section 104. As such, flow restrictor section 406 is operable to restrict the flow rate of the production fluids through fluid flow control device 400.

Once the production fluids pass through flow rate controller 430 of flow restrictor section 406, they enter annular chamber 434 and eventually enter the interior of base pipe 418 via openings 436 which are depicted in the form of slots. Once inside base pipe 418, the production fluids flow to the surface within the tubing string.

Like fluid flow control device 300 of FIG. 4, fluid flow control device 400 is specifically designed for operation in three phase flow. As illustrated, one group of members 424 is separated from another group of members 424 by a pair of spacers 438. Spacers 438 each have a flow path therethrough that provides for fluid communication from chamber 416 to outlets 422. The system of members 424 and spacers 438 are relatively tightly received between retainer rings 420, 421 simulating the action of roller bearings in a race. In the illustrated embodiment, the system of members 424 and spacers 438 is self orienting based upon the flow regime within fluid flow control device 400, gravity or both. For example, each of the members 424 above spacers 438 may have a density less than that of oil while the members 424 below spacers 438 may have a density greater than that of oil. Alternatively or additionally, certain of the members 424 below spacers 438 may have a substantially greater weight than any of the other members 424 such that in a horizontal implementation the self orientation results in the configuration depicted in FIG. 5B.

In either embodiment, members 424 are designed to cooperate with outlets 422 to block or at least restrict the production of the undesired fluid streams of water and gas in an oil production operation. Specifically, the members 424 above spacers 438 are intended to block or at least restrict the production of gas while the members 424 below spacers 438 are intended to block or at least restrict the production of water.

Referring next to FIGS. 6A-6B, therein is depicted a fluid flow control device according to the present invention that is representatively illustrated and generally designated 500. Fluid flow control device 500 may be suitably coupled to other similar fluid flow control devices, production packers, production tubulars or other downhole tools to form a tubing string as described above. Fluid flow control device 500 includes a sand control screen section 502, a fluid discriminator section 504, a flow restrictor section 506 and a fluid inlet section 508. Sand control screen section 502 includes a suitable sand control screen element or filter medium and is illustrated as including a protective outer shroud 510 having a plurality of perforations 512 positioned around the exterior of the filter medium.

Fluid discriminator section 504 is configured in series with sand control screen section 502 such that fluid must pass through sand control screen section 502 prior to entering fluid discriminator section 504. Fluid discriminator section 504 includes an outer housing 514 that defines an annular chamber 516 with a nonperforated section of base pipe 518. Fluid discriminator section 504 also includes retainer rings 520, 521. Retainer ring 520 has a plurality of outlets 522 circumferentially spaced therein designed to provide a fluid passageway from chamber 516 to flow restrictor section 506. Disposed within chamber 516 between retainer rings 520, 521 and designed to cooperate with outlets 522 to restrict the flow of any undesired portion of the production fluids that enter fluid discriminator section 504 is a plurality of flow blocking members 524, depicted as partially circumferential members.

Flow restrictor section 506 is configured in series with fluid discriminator section 504 such that fluid must pass through fluid discriminator section 504 prior to entering flow restrictor section 506. Flow restrictor section 506 includes an outer housing 526 that is suitably coupled to outer housing 514 of fluid discriminator section 504. Outer housing 526 defines an annular chamber 528 with a nonperforated section of base pipe 518. Disposed within chamber 528 is an annular flow rate controller 530. Flow rate controller 530 includes one or more helical passageways 532 that provide a relative long pathway for the fluids to travel within flow restrictor section 506 and that provide a more restrictive pathway than the unrestricted pathway through fluid discriminator section 504 in a manner similar to that described above with reference to flow restrictor section 106 and fluid discriminator section 104. As such, flow restrictor section 506 is operable to restrict the flow rate of the production fluids through fluid flow control device 500.

Once the production fluids pass through flow rate controller 530 of flow restrictor section 506, they enter annular chamber 534 and eventually enter the interior of base pipe 518 via openings 536 which are depicted in the form of slots. Once inside base pipe 518, the production fluids flow to the surface within the tubing string.

Like fluid flow control device 300 of FIG. 4, fluid flow control device 500 is specifically designed for operation in three phase flow. As illustrated, a single upper member 524 is separated from three lower members 524 by a pair of spacers 538. Spacers 538 each have a flow path therethrough that provides for fluid communication from chamber 516 to outlets 522. The system of members 524 and spacers 538 are relatively tightly received between retainer rings 520, 521 and are allowed to rotation circumferentially therein. In the illustrated embodiment, the system of members 524 and spacers 538 is self orienting based upon the flow regime within fluid flow control device 500, gravity or both. For example, the upper member 524 above spacer 538 may have a density less than that of oil while the lower members 524 below spacers 438 may have a density greater than that of oil. Alternatively or additionally, certain of the members 524 below spacers 538 may have a substantially greater weight than any of the other members 524 such that in a horizontal implementation the self orientation results in the configuration depicted in FIG. 6B.

In either embodiment, members 524 are designed to cooperate with outlets 522 to block or at least restrict the production of the undesired fluid streams of water and gas in an oil production operation. Specifically, the upper member 524 above spacers 538 is intended to block or at least restrict the production of gas while the lower members 524 below spacers 538 are intended to block or at least restrict the production of water.

It may now be fully appreciated that fluid flow control devices of the present invention may have various configurations described above and are capable of achieving a variety of desirable benefits in different situations. For example, when it is desired to limit the production of water from a gas well, the configuration of FIGS. 2B and 3B may be used with the members each having a density approximately equal to, or less than that of water. In this manner, the members will either have neutral buoyancy in the water, or will float on top of the water, such that the members will be carried by the water to the outlets to thereby increasingly restrict or prevent flow of the water therethrough.

As another example, when it is desired to limit the production of gas from an oil well, the configuration of FIGS. 2B and 3B may again be used with the members each having a density less than that of oil. In this manner, the members will float on top of the oil, or remain at the top of the chamber and away from the outlets until a sufficient proportion of gas is produced. If such a sufficient proportion of gas is produced, the members will descend within the chamber and close off or at least increasingly restrict flow through the outlets to thereby restrict or prevent flow of the gas therethrough.

Note that the case of restricting production of gas from an oil well is quite different from the case of restricting production of water from a gas well. When restricting the production of gas from an oil well, the members are preferably not neutrally buoyant in the liquid phase, otherwise the members would be carried with the flow of the liquid to the outlets. When restricting the production of water from a gas well, the members may be neutrally buoyant in the liquid phase, since it is desired for the members to be carried with the flow of the liquid to the outlets to restrict the flow of the liquid therethrough.

As yet another example, when it is desired to limit the production of gas and water from an oil well, the configurations of FIGS. 2D, 3B, 4B, 5B and 6B may be used, with certain members having a density less than that of oil, and certain members having a density greater than that of oil. In this manner, certain members will float on top of the oil, or be oriented to the top of the chamber and away from the outlets until a sufficient proportion of gas is produced to allow the members to close off or at least increasingly restrict flow through the upper outlets to thereby restrict or prevent flow of the gas therethrough. Also, in this manner, certain members will remain toward the bottom of the chamber and away from the outlets until a sufficient proportion of water is produced to allow the members to close off or at least increasingly restrict flow through the lower outlets to thereby restrict or prevent flow of the water therethrough.

While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments. 

1. A flow control apparatus for controlling the inflow of production fluids from a subterranean well, the flow control apparatus comprising: a fluid discriminator section; a flow restrictor section configured in series with the fluid discriminator section such that fluid must pass through the fluid discriminator section prior to passing through the flow restrictor section; wherein the fluid discriminator section is operable to autonomously restrict at least a portion of an undesired fluid type from the production fluids; and wherein the flow restrictor section is operable to restrict the flow rate of the production fluids.
 2. The flow control apparatus as recited in claim 1 wherein the fluid discriminator section includes a substantially circumferential chamber having a plurality of circumferentially distributed outlets and a plurality of blocking members disposed within the substantially circumferential chamber.
 3. The flow control apparatus as recited in claim 2 wherein at least a portion of the blocking members have a density greater than that of oil.
 4. The flow control apparatus as recited in claim 2 wherein at least a portion of the blocking members have a density less than that of oil.
 5. The flow control apparatus as recited in claim 2 wherein a first portion of the blocking members have a density greater than that of oil and wherein a second portion of the blocking members have a density less than that of oil.
 6. The flow control apparatus as recited in claim 2 wherein a first portion of the blocking members have a weight that is greater than that of a second portion of the blocking members.
 7. The flow control apparatus as recited in claim 2 further comprising spacer members disposed between at least some of the blocking members.
 8. The flow control apparatus as recited in claim 2 wherein the blocking members are one of spherically shaped, cylindrically shaped and partially circumferentially shaped.
 9. The flow control apparatus as recited in claim 1 wherein the flow restrictor section further comprises a passageway.
 10. The flow control apparatus as recited in claim 9 wherein the passageway has an effective flow area less than about twenty five percent of an unrestricted effective flow area of the fluid discriminator section.
 11. The flow control apparatus as recited in claim 9 wherein the passageway has an effective flow area less than about ten percent of an unrestricted effective flow area of the fluid discriminator section.
 12. The flow control apparatus as recited in claim 9 wherein the passageway further comprises a helical passageway.
 13. The flow control apparatus as recited in claim 9 wherein the passageway further comprises a plurality of helical passageways.
 14. A flow control apparatus for controlling the inflow of production fluids from a subterranean well, the flow control apparatus comprising: a sand control screen element; a fluid discriminator section configured in series with the sand control screen element such that fluid must pass through the sand control screen element prior to passing through the fluid discriminator section; a flow restrictor section configured in series with the fluid discriminator section such that fluid must pass through the fluid discriminator section prior to passing through the flow restrictor section; wherein the fluid discriminator section is operable to autonomously restrict at least a portion of an undesired fluid type from the production fluids; and wherein the flow restrictor section is operable to restrict the flow rate of the production fluids.
 15. The flow control apparatus as recited in claim 14 wherein the fluid discriminator section includes a substantially circumferential chamber having a plurality of circumferentially distributed outlets and a plurality of blocking members disposed within the substantially circumferential chamber that cooperate with the outlets to autonomously restrict the at least a portion of the undesired fluid type from the production fluids.
 16. The flow control apparatus as recited in claim 14 wherein a first portion of the blocking members have a density greater than that of oil and wherein a second portion of the blocking members have a density less than that of oil.
 17. The flow control apparatus as recited in claim 14 wherein the flow restrictor section further comprises a passageway having an effective flow area less than twenty five about percent of an unrestricted effective flow area of the fluid discriminator section.
 18. The flow control apparatus as recited in claim 14 wherein the flow restrictor section further comprises a helical passageway.
 19. A flow control apparatus for controlling the inflow of production fluids from a subterranean well, the flow control apparatus comprising: a fluid discriminator section; a flow restrictor section configured in series with the fluid discriminator section such that fluid must pass through the fluid discriminator section prior to passing through the flow restrictor section; wherein the fluid discriminator section includes a substantially circumferential chamber having a plurality of circumferentially distributed outlets and a plurality of blocking members disposed within the substantially circumferential chamber that cooperate with the outlets to autonomously restrict at least a portion of an undesired fluid type from the production fluids; and wherein the flow restrictor section includes a helical passageway having an effective flow area less than twenty five about percent of an unrestricted effective flow area of the fluid discriminator section such that the flow restrictor section is operable to restrict the flow rate of the production fluids.
 20. The flow control apparatus as recited in claim 19 wherein a first portion of the blocking members have a density greater than that of oil and wherein a second portion of the blocking members have a density less than that of oil. 